CompressX Documentation

Everything you need to install, configure, and get the best performance from CompressX Free and Pro.

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Thumbnail Re-generation & Quick Start

Dec 31, 2025 | Docs

Thumbnail re-generation allows you to rebuild the thumbnails (PNG/JPG, Webp and/or AVIF) of all image sizes based on the current settings.

What is Thumbnail Re-generation?

Thumbnail Re-generation allows you to regenerate all image thumbnail sizes based on your current WordPress and CompressX settings.
This process recreates thumbnails for all supported formats, including PNG, JPG, WebP, and AVIF (if enabled), ensuring that your media library stays consistent with your latest configuration.

Is it safe to use?

Yes. When used correctly, Thumbnail Re-generation is safe.
CompressX Pro uses standard WordPress media APIs to regenerate thumbnails, following WordPress best practices. This ensures maximum compatibility with most themes and plugins.
We are also continuously improving compatibility with themes or plugins that do not fully follow WordPress standards.

Note
Images uploaded outside the WordPress Media Library (for example, via FTP or third-party tools) are not processed by CompressX Pro, as they are not registered through WordPress media APIs.

Quick Start (Bulk Regeneration)

Starting a bulk thumbnail re-generation is simple.

Compress pro thumbnail regen

In most cases, you don’t need to change any settings. Just click the Regenerate Thumbnails button and let CompressX handle the rest.
Not sure if thumbnail re-generation is needed for your site?
See When to Use Thumbnail Re-Generation for common scenarios and best practices.
Before starting, one of the situations you should confirm is whether you have added new thumbnail sizes (for example, via a theme or plugin). If you’re unsure whether thumbnail re-generation is necessary in your situation, please refer to When to Use Thumbnail Re-Generation for practical use cases and recommendations.

Advanced Settings

For detailed explanations of each Thumbnail Re-generation option, please refer to the Settings documentation.